Hybridization in North American Asclepias. III. Isozyme Evidence
Hybridization in North American Asclepias. III. Isozyme Evidence
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北美马利筋的杂交。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
S. B. Broyles
中科院分区：
文献类型：
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作者：
R. Wyatt;S. B. Broyles
我们沿着西弗吉尼亚州东北部多莉索兹荒野地区3公里的横断面采集了100棵成年乳草样本。对这些植株进行了13个花性状和17个叶性状的测定。我们还使用水平淀粉凝胶电泳评分11个酶位点的变化。构建了一个复合性状指数，该指数对A. syriaca和A. exaltata。来自样带中部的30株植物变异性很大，许多植物的得分接近于零。这些植物大概代表了一个复杂的杂种群，包括F，种间杂种和回交。具有中间特征指数得分的植物比具有较高特征指数得分的植物更可能不开花（A。（A）低，低叙利亚式）得分。仅根据生殖特征的研究，人们可能会得出结论，没有杂交的证据，因为在54种开花植物中似乎没有中间体。然而，营养特征，揭示了一个更复杂的模式的变化，同意更好地与所有100株植物的同工酶分析。这表明A. exaltata和A.在多利索兹地区的叙利亚。马利筋繁殖的几个独特的特征似乎促进种间杂交，并放大其效果。
We sampled 100 adult milkweeds along a 3 km transect through the Dolly Sods Wilderness Area in northeastern West Virginia. These plants were measured for 13 flower and 17 leaf characters. We also used horizontal starch-gel electrophoresis to score variation in 11 enzyme loci. A composite character index was constructed that yielded negative scores for species-specific alleles of A. syriaca and positive scores for species-specific alleles of A. exaltata. The 30 plants from the middle portion of the transect were highly variable, with many plants achieving scores near zero. These plants presumably represent a complex hybrid swarm, consisting of F, interspecific hybrids and backcrosses. Plants with intermediate character-index scores were significantly more likely not to flower than were plants with higher (A. exaltata-like) or, especially, lower (A. syriaca- like) scores. On the basis of a study of reproductive characters alone, one might conclude that there is no evidence of hybridization, as there appear to be no intermediates among the 54 flowering plants. Vegetative characters, however, reveal a more complex pattern of variation that agrees better with the isozyme analysis of all 100 plants. It does appear that hybridization and localized in- trogression are occurring between A. exaltata and A. syriaca in the Dolly Sods region. Several unique features of milkweed reproduction appear to promote interspecific hybridization and to magnify its effects.